A personal series of 141 patients with postanal pilonidal sinus was treated by the Karydakis operation. Each sinus was totally excised with a vertical eccentric elliptical excision. A thick flap was created by undercutting the medial edge and advancing it across the midline so that the whole suture line was lateralized to reduce the risk of recurrence. Follow-up was achieved in 114 patients for 1–108 months; 79 (69 per cent) were followed for more than 18 months. Overall there were five recurrences (4 per cent) which required further surgery. Thirty-three patients (23 per cent) were referred following recurrence or failure of healing after previous surgery elsewhere; all were cured by this method. The Karydakis operation has a low recurrence rate because it produces a shallow midline furrow free from scar or suture holes which is less vulnerable to hair penetration than a midline wound.